1. Field of the Invention
This invention is related to jointed elastomer-coated fabric material such as is used as roofing material for large structures.
2. Background Information
Elastomer-coated fabric has conventionally been used as a waterproof fabric, for diving suits, as belts and as a fireproof curtain and it has recently been proposed as a roofing material for stadiums, gymnasiums and outdoor restaurants.
In U.S. Pat. No. 4,192,116, issued Mar. 11, 1980, to Kelly, a method of joining adjacent cured rubber membranes for use in a roof construction is taught. The lapping ends of the cured rubber membranes are sealed together with cement or the like, then an additional sealing means is provided. A composite structure comprising a lower uncured gum rubber strip and a cured reinforced rubber is applied over the seam and caused to be adhered to both portions of both of the overlapping membranes.
In U.S. Pat. No. 4,303,712, issued Dec. 1, 1981, to Woodroof, a fabric elastomer composite useful for various garments is described. The composite is a relatively thin elastomer membrane having a stretchable fabric joined thereto. He illustrates various methods of forming water tight joints in which adjacent pieces are sewn together. The sewn joint is then covered with a fabric elastomer strip which is bonded to the pieces of composite on each side of the sewn joint by means of a bead of room temperature vulcanizing silicone rubber applied between the composite and the fabric elastomer strip.
It is difficult to manufacture elastomer-coated cloth with a large surface area. However, because large surface areas are required when elastomer-coated cloths are to be used for building roofing materials and for large-scale tent materials, numerous pieces with a comparatively small surface area as manufactured in the factory must be joined.
To join one fabric with another fabric, the edges of the fabrics are overlaid on each other and then sewn by the usual method. This method is generally satisfactory for the production of jointed materials with small areas. However, when the fabrics are to be joined together with each other in order to manufacture a large roofing substitute for a building or large-scale tenting, this method in which only the edges of the fabrics are overlaid on each other and then sewn suffers drawbacks such as low strength and poor watertightness. The tensile stresses generated by gravity and wind pressure will concentrate in the vicinity of the sewn thread with a resulting ready rupture in this region. Also, rainwater and dust will infiltrate through this gap in the overlaid region.
The purpose of this invention is to eliminate the above-mentioned drawbacks and to provide a jointed elastomer-coated fabric material which exhibits high strength, excellent watertightness, and excellent airtightness.